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Vaccine hesitancy
Vaccine hesitancy, a reluctance or refusal to be vaccinated or to have one's children vaccinated, is identified by the World Health Organization as one of the top ten global health threats of 2019. Arguments against vaccination are contradicted by overwhelming scientific consensus about the safety and efficacy of vaccines. Hesitancy results from public debates around the medical, ethical and legal issues related to vaccines. It has existed since the invention of vaccination, and pre-dates the coining of the terms "vaccine" and "vaccination" by nearly 80 years. The specific hypotheses raised by anti-vaccination advocates have been found to change over time. Vaccine hesitancy often results in disease outbreaks and deaths from vaccine-preventable diseases. Bills for mandatory vaccination have been considered for legislation, including California Senate Bill 277 and Australia's No Jab No Pay, all of which have been strenuously opposed by anti-vaccination activists. Opposition to mandatory vaccination may be based on anti-vaccine sentiment, or concern that it violates civil liberties or reduces public trust in vaccination. Effectiveness Scientific evidence for the effectiveness of large-scale vaccination campaigns is well established. Vaccination campaigns helped eradicate smallpox, which once killed as many as one in seven children in Europe, and have nearly eradicated polio. As a more modest example, infections caused by Haemophilus influenzae (Hib), a major cause of bacterial meningitis and other serious diseases in children, have decreased by over 99% in the US since the introduction of a vaccine in 1988. It is estimated that full vaccination, from birth to adolescence, of all US children born in a given year would save 33,000 lives and prevent 14 million infections. Some argue that these reductions in infectious disease are a result of improved sanitation and hygiene (rather than vaccination), or that these diseases were already in decline before the introduction of specific vaccines. These claims are not supported by scientific data; the incidence of vaccine-preventable diseases tended to fluctuate over time until the introduction of specific vaccines, at which point the incidence dropped to near zero. A Centers for Disease Control website aimed at countering common misconceptions about vaccines argued, "Are we expected to believe that better sanitation caused incidence of each disease to drop, just at the time a vaccine for that disease was introduced?" Other critics argue that the immunity granted by vaccines is only temporary and requires boosters, whereas those who survive the disease become permanently immune. As discussed below, the philosophies of some alternative medicine practitioners are incompatible with the idea that vaccines are effective. Population health , who had all four limbs partially amputated aged seven months due to meningococcal disease. More widespread vaccination can protect children like Cleverley-Bisman, who are too young to vaccinate, from catching the disease through development of herd immunity. ]] Incomplete vaccine coverage increases the risk of disease for the entire population, including those who have been vaccinated, because it reduces herd immunity. For example, the measles vaccine is given to children between the ages of 9 and 12 months, and the short window between the disappearance of maternal antibody (before which the vaccine often fails to seroconvert) and natural infection means that vaccinated children are frequently still vulnerable. Herd immunity lessens this vulnerability if all the children are vaccinated. Increasing herd immunity during an outbreak or risk of outbreak is perhaps the most widely accepted justification for mass vaccination. When a new vaccine is introduced mass vaccination helps increase coverage rapidly. If enough of a population is vaccinated, herd immunity takes effect, decreasing risk to people who cannot receive vaccines because they are too young or old, immunocompromised, or have severe allergies to the ingredients in the vaccine. The outcome for people with compromised immune systems who get infected is often worse than that of the general population. Common themes While some anti-vaccinationists openly deny the improvements vaccination has made to public health, or succumb to conspiracy theories, it is much more common to cite concerns about safety. As with any medical treatment, there is a potential for vaccines to cause serious complications, such as severe allergic reactions, but unlike most other medical interventions, vaccines are given to healthy people and so a higher standard of safety is expected. While serious complications from vaccinations are possible, they are extremely rare and much less common than similar risks from the diseases they prevent. As the success of immunization programs increases and the incidence of disease decreases, public attention shifts away from the risks of disease to the risk of vaccination, and it becomes challenging for health authorities to preserve public support for vaccination programs. Concerns about immunization safety often follow a pattern. First, some investigators suggest that a medical condition of increasing prevalence or unknown cause is an adverse effect of vaccination. The initial study and subsequent studies by the same group have inadequate methodology—typically a poorly controlled or uncontrolled case series. A premature announcement is made about the alleged adverse effect, resonating with individuals suffering from the condition, and underestimating the potential harm of forgoing vaccination to those whom the vaccine could protect. Other groups attempt to replicate the initial study but fail to get the same results. Finally, it takes several years to regain public confidence in the vaccine. Adverse effects ascribed to vaccines typically have an unknown origin, an increasing incidence, some biological plausibility, occurrences close to the time of vaccination, and dreaded outcomes. In almost all cases, the public health effect is limited by cultural boundaries: English speakers worry about one vaccine causing autism, while French speakers worry about another vaccine causing multiple sclerosis, and Nigerians worry that a third vaccine causes infertility. 'Autism' The idea of a link between vaccines and autism has been extensively investigated and shown to be false. The scientific consensus is that there is no relationship, causal or otherwise, between vaccines and incidence of autism, and vaccine ingredients do not cause autism. Nevertheless, the anti-vaccination movement continues to promote myths, conspiracy theories and misinformation linking the two. A developing tactic appears to be the "promotion of irrelevant research as an active aggregation of several questionable or peripherally related research studies in an attempt to justify the science underlying a questionable claim." 'Thiomersal' Thiomersal (spelled "thimerosal" in the US) is an antifungal preservative used in small amounts in some multi-dose vaccines (where the same vial is opened and used for multiple patients) to prevent contamination of the vaccine. Despite thiomersal's efficacy, the use of thiomersal is controversial because it contains mercury. As a result, in 1999, the Centers for Disease Control (CDC) and the American Academy of Pediatrics (AAP) asked vaccine makers to remove thiomersal from vaccines as quickly as possible on the precautionary principle. Thiomersal is now absent from all common US and European vaccines, except for some preparations of influenza vaccine. Trace amounts remain in some vaccines due to production processes, at an approximate maximum of 1 microgramme, around 15% of the average daily mercury intake in the US for adults and 2.5% of the daily level considered tolerable by the WHO. The action sparked concern that thiomersal could have been responsible for autism. The idea is now considered disproven, as incidence rates for autism increased steadily even after thiomersal was removed from childhood vaccines. Currently there is no accepted scientific evidence that exposure to thiomersal is a factor in causing autism. Since 2000, parents in the United States have pursued legal compensation from a federal fund arguing that thiomersal caused autism in their children. A 2004 Institute of Medicine (IOM) committee favored rejecting any causal relationship between thiomersal-containing vaccines and autism. 'MMR vaccine' In the UK, the MMR vaccine was the subject of controversy after the publication in The Lancet of a 1998 paper by Andrew Wakefield and others reporting case histories of 12 children mostly with autism spectrum disorders with onset soon after administration of the vaccine. At a 1998 press conference, Wakefield suggested that giving children the vaccines in three separate doses would be safer than a single vaccination. This suggestion was not supported by the paper, and several subsequent peer-reviewed studies have failed to show any association between the vaccine and autism. It later emerged that Wakefield had received funding from litigants against vaccine manufacturers and that he had not informed colleagues or medical authorities of his conflict of interest; had this been known, publication in The Lancet would not have taken place in the way that it did. Wakefield has been heavily criticized on scientific grounds and for triggering a decline in vaccination rates (vaccination rates in the UK dropped to 80% in the years following the study), as well as on ethical grounds for the way the research was conducted. In 2004, the MMR-and-autism interpretation of the paper was formally retracted by 10 of Wakefield's 12 coauthors, and in 2010 The Lancet s editors fully retracted the paper. Wakefield was struck off the UK medical register, with a statement identifying deliberate falsification in the research published in The Lancet, and is barred from practising medicine in the UK. The CDC, the IOM of the National Academy of Sciences, and the UK National Health ServiceMMR Fact Sheet , from the United Kingdom National Health Service. Retrieved June 13, 2007. have all concluded that there is no evidence of a link between the MMR vaccine and autism. A systematic review by the Cochrane Library concluded that there is no credible link between the MMR vaccine and autism, that MMR has prevented diseases that still carry a heavy burden of death and complications, that the lack of confidence in MMR has damaged public health, and that the design and reporting of safety outcomes in MMR vaccine studies are largely inadequate. In 2009, The Sunday Times reported that Wakefield had manipulated patient data and misreported results in his 1998 paper, creating the appearance of a link with autism. A 2011 article in the ''British Medical Journal'' described how the data in the study had been falsified by Wakefield so that it would arrive at a predetermined conclusion. An accompanying editorial in the same journal described Wakefield's work as an "elaborate fraud" that led to lower vaccination rates, putting hundreds of thousands of children at risk and diverting energy and money away from research into the true cause of autism. A special court convened in the United States to review claims under the National Vaccine Injury Compensation Program ruled on February 12, 2009 that parents of autistic children are not entitled to compensation in their contention that certain vaccines caused autism in their children.Vaccine court and autism: * * References * Category:Autism pseudoscience